Hi,
If you are referring to the protruding cheek bones, teeth and forehead, then it is due to expansion of overworking bone marrow.
This happens when the child is not transfused on time to give the Bone marrow rest in the early age when the child is growing and the bones are fragile and get easily deformed.
To avoid such a thing from happening, always keep the pretransfusion HB in check and don't let it go down too much.
Take care.